Unless otherwise indicated herein, the description in this section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section.
A typical image forming apparatus, such as a copying machine, a printer, a facsimile, or a multi-functional peripheral including these functions, is equipped with a sheet conveyance apparatus that conveys a sheet. Such sheet conveyance apparatus includes a conveyance roller pair that forms a nip portion where the sheet passes. A rotary drive power being input to one roller of the conveyance roller pair from a driving unit causes the conveyance roller pair in convey the sheet to a predetermined conveyance direction.
Recently, in order to improve a productivity of the image forming apparatus, there has been developed a technique that variably controls sheet conveyance speeds and decreases a spacing between sheets. In order to control the sheet conveyance speed, a stepper motor is typically selected as a driving unit. However, since the stepper motor has a large power consumption, a servo control of a brushless motor is recently getting to be a mainstream, especially, a brushless motor of an inner brushless type is often employed. There has been proposed a technique in which the brushless motor generates the rotary drive power input to the conveyance roller.